An OLED (Organic Light-Emitting Diode) display is an all-solid and active light-emitting display. The OLED display, due to its advantages of high luminance, high contrast, ultra-thin and ultra-light properties, low power consumption, no view angle restriction, wide range of working temperature, etc., is regarded as a new application technology for the next generation of flat panel displays. The packaging method of the OLED device is a key technology of the OLED display that is different from those of other displays. The OLED device is made of an organic material which will undergo irreversible photooxidation in the presence of moisture and oxygen. In addition, water and oxygen are highly erosive to electrode materials such as aluminum, magnesium, silver, or the like. Hence, the packaging of the OLED device has very high requirements on the permeability of water and oxygen.
An existing OLED device packaging technology is “UV+rear package cap”. As shown in FIG. 1, in this technology, first, a desiccant 7 for absorbing moisture is stuck onto the rear package cap 6, then a UV adhesive 9 is applied onto the circumference of an OLED glass substrate 8, and finally, the rear package cap 6 is aligned and attached to the OLED glass substrate 8, and the adhesive 9 (i.e. UV adhesive) is cured with ultraviolet ray. Though this technology has advantages such as mature technology and low cost of equipment, it has the following disadvantages: poor sealing performance, easy permeation of water and oxygen, and inapplicability to top-emitting OLED displays, flexible OLED displays and large-size OLED displays; and as the desiccant 7 is stuck onto the rear package cap 6, the thickness and volume of the OLED display are increased to some extent.
In order to thin the OLED display and increase the air tightness of package, another existing packaging technology is laser sintering frit packaging technology (Frit). The sealing performance of this method is excellent and much better than that of traditional UV resin. As shown in FIG. 2, a layer of frit with a low softening point, having a width approximately from 1 mm to 2 mm and a thickness approximately from 6 μm to 100 μm, is deposited onto edges of the rear package cap 6 by silk-screen printing. Then, organics in the frit are removed by pre-baking to cure the frit. Then, the frit is heated by laser radiation, to melt the frit and to bond the frit to the OLED glass substrate 8 and the rear package cap 6, in order to form a glass wall 10. However, there are still some problems for this packaging technology. With the radiation onto the frit by laser, the thickness of the glass wall 10, formed after the frit is melted, is gradually increased, so that the energy of the laser is gradually weakened with the increase of incident depth in the glass wall 10, thus, not all frit contained in the glass wall 10 may be melted by laser. This will result in that there are a great number of holes and cracks in the glass wall 10, the holes and the cracks provide channels for permeation of moisture and oxygen into the OLED device 11, and thus the service life of the OLED device 11 is greatly reduced.